The present invention relates to a technology of manufacturing a semiconductor device, and more particularly, to a resistive memory device which utilizes a change in resistance, such as in nonvolatile Resistive Random Access Memory (ReRAM) devices, and a method for manufacturing the same.
Recently, researchers are actively studying next-generation semiconductor memory devices which can replace Dynamic Random Access Memory (DRAM) and flash memory.
One of such next-generation semiconductor memory devices is a resistive memory device utilizing a material whose resistance changes rapidly according to an applied bias to switch between at least two different resistance states, that is, a resistive layer. As a resistive layer having such characteristics, binary oxide including transition metal oxide or perovskite-based material has been used.
The structure of the resistive memory device and its switching mechanism are briefly described hereinafter.
Generally, a resistive memory device has a structure including upper and lower electrodes and a resistive layer located between the upper and lower electrodes. When a predetermined bias is applied to the upper and lower electrodes, a filamentary current path may be generated due to oxygen vacancies in the resistive layer, or the generated filamentary current path may disappear following the elimination of the generated oxygen vacancies. The resistive layer represents two resistive states which are distinguished from each other due to the generation or elimination of the filamentary current path. That is, when the filamentary current path is generated, a state where resistance is low, that is, a set state, is formed, and when the filamentary current path is eliminated, a state where resistance is high, that is, a reset state, is formed.
However, repeated write/erase operations of the resistive memory device may cause a set-stuck phenomenon, in which it is impossible to return from a set state to a reset state. In order to return from the set state to the reset state, it is required to fill oxygen vacancies with oxygen of an upper electrode interface to eliminate the filamentary current path. However, since the oxygen of the upper electrode interface is diffused out as time passes, the oxygen around the upper electrode interface becomes insufficient.
As a result, the resistive memory device is weak with respect to an endurance of framework, and this property makes it difficult to substantially utilize the resistive memory device as a memory device.